Ligand-binding characteristics of feline insulin-binding immunoglobulin G

Polyclonal immunoglobulin (Ig) G autoantibodies against insulin have been identified in sera of healthy cats. We purified and fractionated insulin-binding IgGs from cat sera by affinity chromatography and analyzed affinity of insulin-binding IgGs for insulin and their epitopes. Following the passing of fraction A, which did not bind to insulin, insulin-binding IgGs were eluted into two fractions, B and C, by affinity chromatography using a column fixed with bovine insulin. Dissociation constant (KD) values between insulin-binding IgGs and insulin, determined by surface plasmon resonance analysis (Biacore™system), were 1.64e⁻⁴ M for fraction B (low affinity IgGs) and 2e⁻⁵ M for fraction C (high affinity IgGs). Epitope analysis was conducted using 16 peptide fragments synthesized in concord with the amino acid sequence of feline insulin by an enzyme-linked immunosorbent assay. Fractions B and C showed higher absorbance (affinity) of the peptide fragment of 10 amino acid residues at the carboxyl-terminal of the B chain (peptide No. 19), followed by peptide fragments of 6 to 15 amino acid residues of the B chain (peptide No. 8). Fraction C showed a higher absorbance to 7 to 16 amino acid residues of the B chain (peptide No. 5) compared with the absorbance of fraction B. Polyclonal insulin-binding IgGs may form a macromolecule complex with insulin through the multiple affinity sites of IgG molecules. Feline insulin-binding IgGs are multifocal and may be composed of multiple IgG components and insulin.     

碱提甘蔗皮多糖提取工艺、初步结构及其对α-葡萄糖苷酶的抑制作用

【目的】建立碱提甘蔗皮多糖的优化工艺,进一步探究其结构特征,并评价其对α-葡萄糖苷酶的抑制作用。【方法】采用单因素试验和响应面分析法（RSM）对碱提甘蔗皮多糖（SPAP）提取工艺进行优化,采用苯酚硫酸法测定多糖含量。SPAP经Sevag法除蛋白、AB-8除色素后进行结构表征,主要包括高效液相色谱法（HPLC）检测多糖分子量分布,气相-质谱色谱仪（GC-MS）进行单糖分析及傅里叶红外光谱仪（FT-IR）对官能团进行分析。采用4-硝基苯基-D-吡喃葡糖苷（PNPG）法测定多糖提取物对α-葡萄糖苷酶抑制作用。【结果】SPAP的最佳提取条件为提取温度37℃、氢氧化钠（NaOH）浓度5%、料液比1∶46（g·mL^-1）、提取次数4次,在此条件下SPAP得率达到10.84%。经除蛋白、色素后,SPAP含量达到86.54%,主要由阿拉伯糖、木糖、葡萄糖和半乳糖4种单糖组成,分子量为3.03×10³ kD,可能为吡喃型杂多糖,呈现α或β构型。此外,SPAP表现出良好的α-葡萄糖苷酶抑制作用,其抑制率达到78.31%。【结论】对碱提甘蔗皮多糖进行工艺优化,可有效利用原料、提高产出和效率;由HPLC、FT-IR、GC-MS等方面初步阐述了SPAP的结构特性,同时SPAP对α-葡萄糖苷酶表现出良好的抑制作用,具有一定的降糖潜力,研究结果为进一步研究SPAP的构效关系提供了理论依据。     

植物介导金属纳米颗粒合成的研究进展

随着纳米科技的快速发展,人工合成的金属纳米颗粒已在农业生产、生物医药、个人消费品等领域广泛应用。同时,越来越多研究表明植物也能介导金属纳米颗粒的合成。这些研究为制备金属纳米颗粒提供了新思路,但是,多数研究只局限于植物合成方法的表观描述,缺乏对过程及机理的深入研究。这不仅阻碍了金属纳米颗粒与植物相互作用的理论认知,还限制了植物合成方法的大规模应用。本文总结了近年来植物体内金属纳米颗粒的鉴别与表征方法及植物合成纳米材料的应用,重点对植物合成纳米颗粒的过程进行了梳理,发现有机酸、还原性糖类、蛋白质等生物成分都会参与纳米颗粒的生成过程。今后需研发更多的表征手段,以原位技术全面揭示植物合成金属纳米颗粒的机制。     

老化秸秆生物炭对诺氟沙星吸附特性的研究

为研究老化秸秆生物炭的性质及对水中诺氟沙星的吸附特性,本研究将新鲜生物炭进行自然老化、冻融循环老化和高温老化,通过元素分析、扫描电镜和红外光谱分析老化前后生物炭的组成和结构特性变化,研究老化生物炭对诺氟沙星的吸附机理以及pH、离子类型和离子浓度对吸附效果的影响。结果表明：不同老化方式均使生物炭的C元素含量降低,O元素含量显著增加,极性增加,芳香性降低,其中高温老化影响最大。高温老化使生物炭表面的—OH和C=C明显减少,冻融循环老化使—OH数量增加,自然老化对生物炭表面官能团影响较小。老化使生物炭表面破损、孔道塌陷,生物炭上的吸附点位被阻塞,不利于对诺氟沙星的吸附。老化前后生物炭对诺氟沙星的吸附更符合准二级动力学模型,等温吸附拟合发现,Langmuir模型能更好地拟合诺氟沙星在生物炭上的吸附过程。自然老化、冻融循环老化和高温老化分别使生物炭的吸附量降低了5.50%、7.70%、14.80%;在背景液pH 3.0~11.0范围内,老化前后生物炭对诺氟沙星的吸附量随pH增大先升高再降低,当pH为7.0时,吸附量达到最大值。阳离子价态越高,离子浓度越大,老化后生物炭对诺氟沙星的吸附量越小。研究表明,老化对生物炭的理化性质和吸附抗生素的能力均有影响,因此在使用生物炭去除目标污染物时需要考虑环境因素的影响。     

塔里木盆地奥陶系碳酸盐岩缝洞集合体定量地震描述与地质建模

缝洞型碳酸盐岩储层多样多期的地质成因和内部强烈的非均质性,使得常规建模手段难以应用于实际工作中。结合地质体特征和地震相,运用聚类分析技术实现缝洞集合体的几何结构建模;针对缝洞型碳酸盐岩测井资料少、储层内部结构复杂和非均质强的特征,将地质统计学地震反演技术用于储层岩相和孔隙度建模工作中,针对塔里木盆地典型区块缝洞集合体建立静态模型,实现其定量地震描述;进一步利用单井与井组内动态数据,修正缝洞体的规模、边界和连通性,研究成果指导了基于缝洞集合体井位的高效部署、高效开发工作。     

恩诺沙星糖精复合物的制备及其表征

以糖精、恩诺沙星1：2（W／W）制备恩诺沙星糖精复合物。采用x射线粉末衍射、差式扫描热量法、红外分析法进行表征,同时采用抑菌实验和餐食量实验来进一步表征。抑菌实验表明复合物的抑菌作用是原料药的1．6倍左右,餐食量实验表明复合物的餐食量是原料药的1．5倍左右。恩诺沙星糖精复合物制备工艺简单,能够掩盖药物的苦味,适口性好,改善了药物的难溶性。     

Molecular characterization and pathogenicity of a grouper iridovirus (GIV) isolated from yellow grouper, Epinephelus awoara (Temminck & Schlegel)

Molecular characterization was carried out on an iridovirus isolated from yellow grouper, Epinephelus awoara . The major capsid protein (MCP) gene was located, sequenced and compared with homologous genes from other iridoviruses. The nucleotide sequence is 1392 bases long and contains a single open reading frame beginning at an ATG codon from the 5' end and terminating at a TAA codon at the 3' end. The open reading frame encodes a protein of 463 amino acids with a predicted molecular weight of 50 272 Da. Pairwise amino acid alignments detected a high degree of sequence identity between grouper iridovirus (GIV) MCP and the homologous genes of other iridoviruses. The MCP gene of GIV was most similar to the MCP gene from frog virus 3 (FV3) with 70% nucleotide and 73% amino acid sequence identity. The predicted molecular weight of the protein of this gene is comparable with the apparent weight obtained by SDS–PAGE. Pathogenicity of the GIV was investigated in yellow grouper by intraperitoneal injection of 10⁷ and 10⁴ TCID₅₀ virus. Cumulative mortalities reached 100% within 11 and 25 days post-infection, respectively, while no grouper died in the control group. The molecular studies demonstrated that GIV is a member of the genus Ranavirus .     

Isolation,in vitro propagation,genetic analysis,and immunogenic characterization of an Ehrlichia canis strain from southeastern Brazil

Amplification of the 16S rRNA gene from a blood sample obtained from a dog in southeastern Brazil was used to confirm a naturally acquired Ehrlichia (E.) canis infection. Following isolation and culturing of the new bacterial strain called Uberlândia, partial sequences of the dsb and p28 genes were obtained. The dsb partial sequence of the novel strain was 100% similar to dsb gene sequences of E. canis obtained from different geographic areas around the world. Conversely, the p28 partial sequence for the E. canis Uberlândia strain differed at several nucleotides from other sequences available in GenBank. To confirm the antigenic profile of the Uberlândia strain, an indirect immunofluorescence assay against E. canis antigens was performed using dog sera collected from two different areas in Brazil (Uberlândia and São Paulo). The results suggest that both antigens were able to identify animals seropositive for E. canis in Brazil since these Brazilian strains appear to be highly conserved.     

Distribution,quantitative load and characterization of Salmonella associated with swine farms in upper-northern Thailand

This study was conducted to analyze the prevalence and quantitative loads of Salmonella spp. on pig farms in Chiang Mai, Lamphun, Thailand to assess loading levels before slaughtering. The serotype diversity, antimicrobial-resistance pattern and pulse-field type of Salmonella spp. were also characterized to assess the dynamic propagation of the pathogen. The Salmonella-positive prevalence was 246/805 (30.56%), and the quantitative loads varied from 1.48~4.04 Log₁₀MPN/g, with a mean ± standard deviation of 2.11 ± 0.57. AMP/S/TE (ampicillin/streptomycin/tetracycline) was the highest frequency antimicrobial resistance pattern found in this study. In addition, Salmonella Rissen was the primary serotype in this region. PFGE results indicated the occurrence of infection by cross contamination among pig farms. Our study showed that pork is easily contaminated with this pathogen. Farm control programs must be based on strict biosecurity and hygienic measures, which could further reduce the contamination pressure at slaughterhouses or retail shops.     

新疆石河子地区奶牛乳房炎大肠杆菌的分离鉴定及耐药性分析简

本试验旨在调查新疆石河子地区奶牛乳房炎源大肠杆菌的某些生物学特性及其耐药状况,以提高药物疗效,减少牛奶中药物的残留。试验从新疆石河子地区患乳房炎奶牛的乳样中分离纯化并鉴定出21株大肠杆菌,并对大肠杆菌分离株进行抗菌药物敏感性分析。结果表明,21株大肠杆菌对21种抗菌药物中的6种药物耐药率超过50%,其中最多的耐药15种,最少的耐药5种,耐药6及6种以上的菌株共占到76.19%。提示,该地区奶牛乳房炎源大肠杆菌对多种药物已产生了不同程度的耐药性,且存在严重的多重耐药情况。